Inhibitory effects of apple polyphenol extract (AP) and procyanidin contained in AP on in vitro pancreatic lipase activity and in vivo triglyceride absorption in mice and humans were examined. AP and procyanidin considerably inhibited in vitro pancreatic lipase activity. However, polyphenols, except for procyanidin, in AP (i.e., catechins, chalcones, and phenol carboxylic acids) showed weak inhibitory activities on pancreatic lipase. Procyanidins separated by normal-phase chromatography according to the degree of polymerization were also examined. Inhibitory effects of procyanidins increased according to the degree of polymerization from dimer to pentamer. On the other hand, pentamer or greater procyanidins showed maximal inhibitory effects on pancreatic lipase. These results suggested that with respect to in vitro pancreatic lipase inhibition, the degree of polymerization was an important factor and oligomeric procyanidin mainly contributed. Next, we performed a triglyceride tolerance test in mice and humans. Simultaneous ingestion of AP and triglyceride significantly inhibited an increase of plasma triglyceride levels in both models. These results suggested that the oligomeric procyanidins contained in AP inhibited triglyceride absorption by inhibiting pancreatic lipase activity in mice and humans.

In this study, we investigated the absorption of apple procyanidins, namely, apple condensed tannins (ACTs), in rats using the Porter method and high-performance liquid chromatography/tandem mass spectrometry. The apple procyanidin concentrations in the rat plasma reached a maximum 2 h after administration and decreased thereafter. To investigate the limits of the absorption of apple procyanidins in the polymerization degree, we administered the procyanidin oligomer fraction, which was separated from ACT using normal-phase chromatography according to the degree of polymerization. Procyanidins from each dimer to pentamer group were detected in the plasma by the Porter method. Moreover, by the study using reconstituted procyanidins, polymeric procyanidins influenced the absorption of procyanidin oligomers. These results suggest that ACTs are absorbed and directly involved in physiological functions in the rats.

Over 30 MAK (maintenance of killer) genes are necessary for propagation of the killer toxin-encoding M 1 satellite double-stranded RNA of the L-A virus. Sequence analysis revealed that MAK7 is RPL4A, one of the two genes encoding ribosomal protein L4 of the 60S subunit. We further found that mutants with mutations in 18 MAK genes (including mak1 [top1], mak7 [rpl4A], mak8 [rpl3], mak11, and mak16) had decreased free 60S subunits. Mutants with another three mak mutations had half-mer polysomes, indicative of poor association of 60S and 40S subunits. The rest of the mak mutants, including the mak3 (N-acetyltransferase) mutant, showed a normal profile. The free 60S subunits, L-A copy number, and the amount of L-A coat protein in the mak1, mak7, mak11, and mak16 mutants were raised to the normal level by the respective normal single-copy gene. Our data suggest that most mak mutations affect M 1 propagation by their effects on the supply of proteins from the L-A virus and that the translation of the non-poly(A) L-A mRNA depends critically on the amount of free 60S ribosomal subunits, probably because 60S association with the 40S subunit waiting at the initiator AUG is facilitated by the 3 poly(A).Studies of viral propagation generally concentrate on the activities and interactions of virus-encoded proteins. However, the host environment and particular host components can play a crucial role in whether viral propagation is persistent or causes pathology to the host. This is amply demonstrated by studies of the roles of cellular components in bacteriophage replication and assembly.Studies of the L-A double-stranded RNA (dsRNA) virus and its killer toxin-encoding satellite, M 1 dsRNA, have identified many genes of its host, Saccharomyces cerevisiae, which either repress viral propagation (the SKI genes, so named for the superkiller phenotype of mutants in these genes) or are necessary for M 1 propagation (MAK genes, for maintenance of killer). Recently, the SKI2, SKI3, and SKI8 genes have been shown to act by specifically repressing the translation of nonpoly(A) mRNAs, such as the L-A and M 1 mRNAs (28a). In this report, we examine the mechanism by which most of the MAK genes promote viral propagation.The L-A dsRNA virus of S. cerevisiae has two open reading frames in its positive strand, the 5Ј gag encoding its major coat protein (Gag) and the 3Ј pol encoding the multifunctional Pol domain of the Gag-Pol fusion protein. M 1 is a dsRNA satellite of L-A, depending on the L-A-encoded Gag and Gag-Pol for its propagation. M 1 itself encodes no proteins required for its propagation but does encode the killer toxin, a secreted heterodimer protein processed out of a 32-kDa preprotoxin. The L-A genome lacks both 5Ј cap and 3Ј poly(A) (10, 42), and viral transcripts made in vitro lack both modifications, although a single uncoded A (or G) residue is found at the 3Ј end of both viral strands (11,42).Mutants isolated by their inability to propagate the M 1 dsRNA identify about 30 chromosomal MAK genes. MAK3 encodes an N-acetyltran...

No abstract